Inhibition of polyurethane hardening

Abstract

Elastomeric polyurethanes, e.g. as prepared by reacting diisocyanate-capped, essentially linear polyester or polyether and polyol suitable for cross-linking thereof, are inhibited against undesired hardening in use or storage by including in the polyurethane-forming reactant mixture a plasticizing composition composed of carboxylate having a 200-1,000 molecular weight and at least two monocyclic aryl radicals per molecule and, based on the weight of said carboxylate, 0.1-5% glycol having a 62-500 molecular weight.

What is claimed is: 
     
       1. An elastomeric polyurethane composition prepared by subjecting to polyurethane-forming reaction conditions an elastomeric polyurethane-forming reactant mixture comprising (a) diisocyanate-capped, essentially linear polyester or polyether, (b) polyol suitable for cross-linking of said polyester or polyether to provide an elastomeric polyurethane, said polyol having more than two reactive hydroxyl groups, (c) polyurethane-plasticizing carboxylate having a molecular weight from about 200 to about 1,000 and at least two monocyclic aryl radicals per molecule and, based on the weight of said carboxylate, from about 0.1% to about 5% (d) glycol having a molecular weight from 62 to about 500. 
     
     
       2. Composition of claim 1, said polyester or polyether having an average molecular weight from about 500 to about 20,000, said polyol having a molecular weight from about 100 to about 500 and said carboxylate having a molecular weight from about 250 to about 500 and no more than two aryl radicals per molecule. 
     
     
       3. Composition of claim 2, said glycol consisting essentially of alkylene glycol having a molecular weight from about 76 to about 250. 
     
     
       4. Composition of claim 3, said mixture containing from about 10 to about 100 parts of said carboxylate per 100 parts by weight (a) plus (b). 
     
     
       5. Composition of claim 4, said (a) consisting essentially of polyester reaction product of α,ω-alkylene glycol containing from two to about six carbon atoms per molecule and α,ω-alkylene dicarboxylic acid containing from about four to about eight carbon atoms per molecule. 
     
     
       6. Composition of claim 5 wherein said polyester has an average molecular weight from about 1,000 to about 6,000 and comprises reaction product of ethylene glycol and adipic acid. 
     
     
       7. Composition of claim 5, said (d) consisting essentially of α,ω-alkylene glycol having a molecular weight from about 90 to about 150. 
     
     
       8. Composition of claim 7, said (d) consisting essentially of diethylene glycol and said composition containing from about 0.5% to about 3% of said diethylene glycol, based on the weight of said carboxylate. 
     
     
       9. In a process for preparing an elastomeric polyurethane by subjecting to polyurethane-forming reaction conditions an elastomeric polyurethane reactant mixture comprising (a) diisocyanate-capped, essentially linear polyester or polyether, (b) polyol suitable for cross-linking of said polyester or polyether to provide an elastomeric polyurethane, said polyol having more than two reactive hydroxyl groups, and (c) plasticizer for said polyurethane, the improvement which comprises using as said plasticizer a carboxylate having a molecular weight from about 200 to about 1,000 and at least two monocyclic aryl radicals per molecule and including in said mixture from about 0.1% to about 5%, based on the weight of said carboxylate, of (d) glycol having a molecular weight from 62 to about 500. 
     
     
       10. Process improvement of claim 9, said polyester or polyether having an average molecular weight from about 500 to about 20,000, said polyol having a molecular weight from about 100 to about 500 and said carboxylate having a molecular weight from about 250 to about 500 and no more than two aryl radicals per molecule. 
     
     
       11. Process improvement of claim 10 wherein (a), (c) and (d) are combined before (b) is added to said mixture. 
     
     
       12. Process improvement of claim 11, said glycol consisting essentially of alkylene glycol having a molecular weight from about 76 to about 250. 
     
     
       13. Process improvement of claim 12, said mixture containing from about 10 to about 100 parts of said carboxylate per 100 parts by weight (a) plus (b). 
     
     
       14. Process improvement of claim 11, said (a) consisting essentially of polyester reaction product of α,ω-alkylene glycol containing from two to about six carbon atoms per molecule and α,ω-alkylene dicarboxylic acid containing from about four to about eight carbon atoms per molecule. 
     
     
       15. Process improvement of claim 14, said polyester comprising reaction product of ethylene glycol and adipic acid. 
     
     
       16. Process improvement of claim 14, said polyester having an average molecular weight from about 1,000 to about 6,000 and said (d) consisting essentially of α,ω-alkylene glycol having a molecular weight from about 90 to about 150. 
     
     
       17. Process improvement of claim 16 wherein from about 0.5% to about 3% diethylene glycol is included in said mixture. 
     
     
       18. Composition consisting essentially of butyl benzyl phthalate and, based on the weight of said phthalate, from about 0.1% to about 5% alkylene glycol having a molecular weight from about 76 to about 250. 
     
     
       19. Composition of claim 18 consisting essentially of said phthalate and, based on the weight of said phthalate, from about 0.5% to about 3% glycol, said glycol consisting essentially of α,ω-alkylene glycol having a molecular weight from about 90 to about 150. 
     
     
       20. Composition of claim 19, said glycol consisting essentially of diethylene glycol.